GnuPG (GNU Privacy Guard) is a GNU utility for encrypting dataand creating digital signatures. GnuPG has advanced key managementcapabilities and is compliant with the proposed OpenPGP Internet standarddescribed in RFC2440. Because GnuPG doesn't use any patented algorithms,it is not compatible with some versions of PGP 2 which use only thepatented IDEA algorithm. See http://www.gnupg.org/why-not-idea.htmlfor information on using IDEA if the patent does not apply to you andyou need to be compatible with these versions of PGP 2.